Inductive energy transmission in connection with motor vehicles is known in the prior art. Inductive energy transmission in this case is usually employed to charge a battery of an electric vehicle. Such an inductive energy transmission may also take place while driving, as is known, for example, from transport systems in the field of logistics. In order to allow an inductive energy transmission while driving, coils energized with alternating current are furthermore normally employed in the roadway, which may have different positions depending on the receiver system, such as, for example, in the middle of the driving lane or at the height of tire tracks, and different strength or magnetic field height.
In such systems in which a traction battery is charged while driving, energy is also withdrawn at the same time from the traction battery in parallel, in order to accelerate the vehicle by means of the drive motors. These energy transfers are associated with large energy losses. Furthermore, the inductive energy transmission while driving has additional drawbacks, for example, as compared to charging while parked: if the energy transmission goes to the suspended mass of the motor vehicle, i.e., to the bodywork, for example to receiver coils arranged on the bottom of the vehicle, a relatively large spacing is required between the ground or the transmitter coils located in the underground base driven upon and the receiver coils situated on the underside of the vehicle, in order to ensure the necessary ground clearance. Accordingly, the transmitter coils must be designed such that magnetic fields are generated that are still sufficiently dense, even at relatively great height above the roadway. Besides a definitely reduced efficiency, this also has the drawback of increased magnetic density. Accordingly, so as not to overly burden the surroundings, for example, pedestrians, etc., the transmitter coils must be energized only in the immediate region of the vehicle, and hence a synchronization with the vehicle position is necessary. In addition to the expense that such a synchronizing entails, the transmitter coils must also be designed correspondingly short for this purpose, i.e., viewed in the direction of travel or the course direction of the roadway, which in turn means a very costly laying of lines and energizing.
While a smaller spacing relative to the roadway can be achieved for an energy transmission to the non-rotating, unsuspended mass of the vehicle, such as, for example, the wheel carrier, nevertheless, it is difficult to arrange the coils next to the tires, given the available structural space.
For an energy transmission to the unsuspended, rotating mass of the vehicle, such as the tires, as is also described in DE 198 24290 A1, a transmission of the received energy must take place from the rotating tire to the wheel carrier, according to the prior art. However, this is associated with a corresponding expense, since it must take place, for example, by sliding contacts or repeated inductive energy transmission, which in turn lessens the efficiency.